CN201114911Y - LED constant current drive circuit - Google Patents

Abstract

The utility model discloses an LED constant current driving circuit, which includes a power module connected to the mains and a lamp group composed of a plurality of light emitting diodes, and is characterized in that: the power module includes an AC power input terminal, a rectifier circuit, an isolation transformer circuit, and a constant current output circuit connected in series in sequence, and the output terminal of the constant current output circuit is connected to the lamp group. Since the utility model is provided with a constant current circuit and adopts a constant current working mode, it can effectively solve the problems of poor brightness uniformity of the light emitting diode and short life of the light emitting diode; and the lighting device adopting the utility model has low power consumption, high brightness, and can achieve the lighting performance of a fluorescent lamp.

Description

A LED constant current drive circuit

Technical field:

The utility model relates to an LED drive circuit, in particular to an LED constant current drive circuit with high power factor which adopts constant current technology and can drive high-power light-emitting diodes to work.

Background technique:

At present, semiconductor lighting (LED) technology is developing rapidly and is gradually replacing the status of fluorescent lamp lighting. The reason for this development trend is that it has the following technical advantages: 1. Good safety: semiconductor light-emitting diodes are organic resins The solid-state device packaged with semiconductor materials and metal materials has a solid structure and will not be loose or broken during normal use, and the luminous body is a cold light source, and the driving circuit does not have high voltage. Therefore, it will not be damaged due to high temperature and broken The internal high voltage causes joint accidents, and its own safety and safety to the external environment are very good. 2. Long service life: The service life of light-emitting diodes is tens of thousands of hours, while the service life of incandescent lamps is often only a few hundred hours, and the nominal service life of fluorescent lamps is only a few thousand hours. Therefore, the service life of semiconductor lighting technology is longer than that of any traditional light source. Both are much longer. 3. High luminous efficiency: In the power range below 3 watts, the luminous efficiency of various light sources is greatly reduced, while the luminous efficiency of the luminous tube is maintained at a relatively high level. The efficiency is much higher than other light sources. 4. Rich colors: LEDs have various colors, which can meet the requirements of various special lighting other than white light. 5. Convenient driving and regulation: LEDs are current-type driving devices, and the brightness can be changed by changing the current value flowing through the LEDs, so the driving and regulation are very convenient. 6. Small size and light weight: semiconductor light-emitting diodes are miniature point light sources, so they can be made into small volume and light weight. 7. There is no heavy metal pollution in discarded devices, which is beneficial to environmental protection. These technological advantages determine that semiconductor light-emitting devices will develop into new lighting sources, change the existing lighting industry structure and market structure, and change people's living environment. The new semiconductor light source requires a special drive circuit to ensure its normal operation. Because the cost per watt of high-power LED is very high (currently generally 10 to 20 yuan/watt), so when driving a high-power LED of 3 watts or more, the cost of the light source is much higher than the cost of the drive, so do a good job of driving The circuit appears to be quite important. At present, the high-power LED drive circuits on the market generally adopt the constant voltage drive mode. The disadvantage of this mode is that with the change of the circuit current, the luminance of each LED will be inconsistent; The damage of a certain LED will cause the current of the whole circuit to increase, which will lead to damage or shorten the life of the entire LED lamp group. In recent years, with the application of high-power and high-brightness laser diodes, their manufacturing costs have gradually decreased, and their luminous effects can fully meet the requirements of fluorescent lighting when combined, but at present, because of the above-mentioned defects in their drive circuits, A large number of applications of LED lamps are restricted.

Utility model content:

Aiming at the above-mentioned technical deficiencies in the existing LED drive circuit with constant voltage mode, the purpose of this utility model is to provide a constant current circuit and an isolation transformer circuit, which can effectively solve the problem of LED brightness uniformity and prolong the life of the LED. High-power LED constant current drive circuit with long life and high power factor.

For realizing the purpose of this utility model, the technical scheme provided is:

A LED constant current drive circuit, which includes a power supply module connected to the mains and a lamp group composed of several light-emitting diodes, characterized in that: the power supply module includes an AC power input terminal and a rectifier circuit connected in series , an isolated transformer circuit, and a constant current output circuit, the output end of the constant current output circuit is connected to a lamp group. The constant current output circuit is formed by connecting a comparator TL431 and a current amplifier circuit.

The LED constant current drive circuit is characterized in that: a common-mode electromagnetic compatibility circuit is connected in series between the input terminal of the AC power supply and the rectifier circuit.

The LED constant current drive circuit is characterized in that a power factor correction circuit is connected in series between the rectification circuit and the isolation transformer circuit.

The LED constant current drive circuit is characterized in that: in the power factor correction circuit, the control input end of the control integrated block is provided with a PC817 current sensing circuit, and the control output end is connected to the negative end of the voltage input coil of the isolation transformer circuit , There is a field effect tube between the neutral line.

The LED constant current drive circuit is characterized in that: the positive output terminal of the voltage of the isolation transformer circuit is connected with a filter circuit.

The LED constant current drive circuit is characterized in that: the rear end of the filter circuit is connected to the constant current output circuit.

The LED constant current drive circuit is characterized in that: the plurality of light emitting diodes are divided into several light groups connected in parallel, wherein each light group is composed of several light emitting diodes connected in series.

The beneficial effects of the utility model are: since the utility model is equipped with a constant current circuit and adopts a constant current working mode, it can effectively solve the problem of brightness uniformity of each LED and prolong the life of the LED; The damage of the LED makes the current of the whole group increase, avoiding the damage of the whole LED lamp group or shortening the life; because it also adopts the working mode of input and output isolation, its output terminal is a safe low voltage; it also adopts EMC circuit, which can Effectively suppress electromagnetic interference; the lighting fixture of the utility model has low power consumption and strong brightness, and the power of a single light-emitting diode tube driven by it can reach 16 watts or more, while its lighting brightness can be equivalent to 80 watts. Fluorescent lamp; the manufacturing cost of the utility model is low, and the mercury pollution phenomenon in the fluorescent lamp will not appear during its manufacturing process and use process, which meets the environmental protection standard; its light brightness can be automatically adjusted so that its lighting brightness meets various lighting requirements. At the same time, due to its low power consumption, it can save a lot of energy, especially there will be no safety problems such as glass material breakage in incandescent bulbs or fluorescent tubes.

Below in conjunction with accompanying drawing and embodiment the utility model is described in further detail.

Description of drawings:

Fig. 1 is the circuit structure block diagram of the utility model embodiment;

FIG. 2 is a schematic circuit diagram of FIG. 1 .

Detailed ways:

Embodiment: Referring to Fig. 1 and Fig. 2, the LED constant current drive circuit provided by the embodiment of the present invention includes an AC power input terminal, an EMC circuit, a rectifier circuit, a power factor correction circuit, an isolation transformer circuit, The constant current output circuit, its input end is connected to the mains, and its output end is connected to the LED light group.

Specifically, this embodiment includes a lamp group composed of 8 light-emitting diodes, wherein the light-emitting diodes of each lamp group are connected in series in sequence; both ends of the lamp group are connected to the output end of the driving circuit; in other embodiments , it is also possible to set multiple groups of LED lamp groups, which are connected in parallel to the output end of the drive circuit. The aforementioned LED constant current drive circuit specifically includes a power supply module, which includes an AC power input terminal connected to the mains, and is sequentially connected to a common-mode EMC circuit, a rectifier circuit, a power factor correction circuit, and an isolation Transformer circuit, a constant current output circuit, the constant current output circuit is connected to the lamp group. The light-emitting diode that adopts in the present embodiment is the LED of 1W 350MA, and its quantity can be at least 1～28, or more. A lamp group is shown in FIG. 2 . The constant current output circuit is formed by connecting a comparator TL431 and a current amplifier circuit.

The aforementioned power factor correction circuit includes a control integrated block and a current sensing circuit. The control input end of the integrated block is connected to the PC817 current sensing circuit, and its control output end is connected to the negative end of the voltage input coil of the isolation transformer circuit (in FIG. 2 5 terminals), a field effect transistor Q2 is set between zero and zero. After the PC817 current sensing circuit senses and conducts the current, the control input terminal is energized, and the control output terminal turns on the field effect transistor Q2, and the field effect transistor Q2 controls the conduction of the voltage input coil circuit. Realize input power factor correction and power output.

The aforementioned isolation and transformation circuit is a mutual induction coil L3, which cuts off the current obtained from the AC input terminal through the transformation of the mutual induction coil L3, and then sends it to the constant current output circuit, which can reduce the influence of fluctuations in the current intensity in the circuit , to achieve a safe power supply to the output.

In the constant current output circuit, the positive terminal of the voltage output terminal of the isolation transformer circuit is directly connected to the diode D7, and then connected to a filter circuit (coil L2). The rear end of the filter circuit is connected to the collector of the triode Q1, the negative terminal of the voltage output terminal of the isolation transformer circuit is connected to the emitter of the triode Q1, and the negative terminal of the lamp group is connected to the base of the triode Q1 through a resistor. The collector of the triode Q1 is positively connected to the comparator TL431, the negative pole of the comparator TL431 is connected to zero, and the positive terminal of the lamp group is connected to the control terminal of the comparator TL431 through a resistor. The control terminal of the comparator TL431 senses the change of the current flowing through the lamp group in real time, and controls the constant current so that the current of the collector of the triode Q1 is within the set current range. In this way, the current output by the emitter will be within the fluctuation range of ±2%, and high-power current output is provided.

As described in the above embodiments, other LED constant current drive circuits obtained by adopting the same or similar structure or design are within the scope of protection of the present invention.

Claims (8)

1, a kind of LED constant-current drive circuit, it comprises that the connection civil power reaches a power module of the lamp group of being made up of several light-emitting diodes, it is characterized in that: described power module, comprise ac power input end, rectification circuit, isolation transforming circuit, the constant current output circuit of serial connection successively, the output of described constant current output circuit connects the lamp group.

2, LED constant-current drive circuit according to claim 1 is characterized in that: described constant current output circuit is formed by connecting by a comparator TL431 and a current amplification circuit.

3, LED constant-current drive circuit according to claim 1 is characterized in that: between described ac power input end and the rectification circuit, also be serially connected with the electromagnetic compatibility circuit of a common mode mode.

4, LED constant-current drive circuit according to claim 1 is characterized in that: also be serially connected with a circuit of power factor correction between described rectification circuit and the isolation transforming circuit.

5, LED constant-current drive circuit according to claim 4, it is characterized in that: in the described circuit of power factor correction, the control input end of its control integrated package is provided with the PC817 current-sensing circuit, is provided with a field effect transistor between the negative pole end of the voltage input line circle of its control output end and isolation transforming circuit, the connecting to neutral line.

6, LED constant-current drive circuit according to claim 1, it is characterized in that: the cathode output end of the voltage of described isolation transforming circuit is connected to filter circuit.

7, LED constant-current drive circuit according to claim 6, it is characterized in that: the rear end of described filter circuit connects described constant current output circuit.

8, LED constant-current drive circuit according to claim 1 is characterized in that: described lamp group is to be composed in series successively by several light-emitting diodes, and it is connected described constant current output circuit output; Several lamp groups are to be connected in parallel on this constant current output circuit output.

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